Professor Baxter’s studies were central in characterising the protein complexes which transport insulin-like growth factors (IGFs), and determining the regulation of the component proteins in cell culture and in vivo. By purifying and developing analytical methods for these and other IGF bioavailability at the cell and whole-body levels. Most recently Baxter’s work has defined structural features of IGF binding proteins that may account for their activities in IGF transport and in cell growth regulation. These studies have increased the understanding of the role of IGFs and their binding proteins in regulating normal body growth and the uncontrolled growth of cancer cells.